Computer servers are composed of processors, memories and other components that are placed on computer blades, themselves embedded in racks inside computer cabinets. A standard computer cabinet usually comprises several racks (or shelves) inside which one or several computer blades is or are embedded.
It is known that embedded computer blades can be cooled by means of an air cooling device. Thus, there are fans at the front of a rack containing computer blades, and air from the fans is forced onto heat sinks located on components of the computer blade that become hot. The hot air that exits from the back of the servers is managed by the air conditioning system in the room in which the server cabinets are located. Such a type of device installed for a 2 m high computer cabinet makes it possible to use cabinet with a maximum power to be dissipated equal to 20 kW, consequently limiting the calculation power of servers.
Another known server cooling device uses the air/water cooling principle. An air/water exchanger is placed at the back of the cabinets. Air passes through the servers, recovers heat dissipated from the servers as its passes and then goes through the air/water exchanger inside which cold water circulates. Cold water circulating in the exchanger is at a temperature of about 7° C. at the inlet for 40 kW and a room temperature of 26° C. As a result the water temperature at the outlet from the cabinet is equal to the air temperature that enters into the cabinet. Thus, for the customer's air conditioning, the cabinet is neutral in terms of air conditioning of the room. Such a system can increase the power that can be generated inside the cabinet up to a maximum of 40 kW that can be dissipated by the air/water cooling device. However, such a device requires a cold water inlet which is not optimum in terms of energy efficiency because it requires the presence of cooling units with compressors inside the room, and these cooling units are particularly energy intensive elements. Furthermore, such a device also limits the available power of such computer cabinets to about 40 kW, consequently limiting the potentially available computer power.
All-hydraulic cooling systems were developed later. This type of cooling system comprises a cold plate located above the components of a computer blade, this cold plate carrying a cooling circuit inside which a liquid coolant circulates. Such a device comprises at least one cold plate picking up heat emitted by computer blades located in the cabinet. The liquid coolant circulates inside each of the cold plates of the computer blades and is then transferred to a water/water exchanger common to the computer blades. Due to the large amount of heat released by the components of the computer blades, water at “ambient temperature” is sufficient to cool them, at the same temperature as the temperature in the room in which the computer server cabinets are located. Thus, there is no longer any need for cold water or hot air to be evacuated and cooled, which considerably reduces the costs of such an installation. However, this type of all-hydraulic cooling creates maintenance problems. The connection between the set of cold plates of computer blades, cooling devices and the water/water exchanger would be made in the bottom of the computer cabinet and manual access to the back of the computer cabinet would be necessary to disconnect the hydraulic connection means between the cold plates and the water/water exchanger, if the computer blades were to be removed/replaced. This constraint introduces other constraints, namely the need for space in the room containing the computer cabinets to allow access behind the computer cabinets and the loss of time associated with this action.